Question

A typical gymnosperms plant has 8 chromosomes in leaf cells. What will be the number of chromosomes in the cells of its gametophyte?
A. 16
B. 8
C. 4
D. 24

Answer 1

Hint: Gymnosperms are a group of nonflowering plants that produce naked seeds or produce seeds without any fruit formation. The seeds are produced in cones and spores on the surface of the leaves or scales. The gametophytic phase involves the production of male and female gametophytes which are haploid cells. Thus, if the gymnosperm plant has 8 chromosomes the gametophyte will have 4 chromosomes.

Complete answer: Gymnosperms are a group of nonflowering vascular plants that are found in several geographical locations in and around the world. The main distinction is that these produce naked seeds in the sense that there is no fruit formation or external covering during seed formation. The seeds are formed from cones or spores on the surface of the leaves or scales of the plant.
Common examples of gymnosperms are ferns, conifers, etc. Gymnosperms reproduce primarily through sporophytic generation. Here the diploid plant produces specialized microspores and megaspores in the pollen cones and ovulates cones of the plant respectively. The pollen grains within the pollen cone mature from the microgametophyte to a microspore (gametophyte), similarly megagametophytes develop from the megaspores in the ovule cone.

Like all gametophytes, both the microspore and the megaspore are haploid. This ensures proper fertilization when the gametes fuse. Thus, if the plant has a diploid cell it would mean that it has 2n chromosomes and the haploid cell of the same plant would have n chromosomes.
Once the microspores (n) and megaspores (n) are matured the pollen is physically deposited onto the ovule cone where fertilization occurs. This pollination is predominantly aided by wind and or insects. After fusion, the zygote develops into a sporophyte (2n).

Thus, for a given plant having a chromosome count of 8, the chromosome in the gametophyte would be 4, therefore the correct option is C.

Note:Gymnosperms have a sporophyte dominant life cycle; this refers to the fact that most vascular tissue and other cellular generation within the plant are sporophytes. Here sporophytes refer to diploid cells. Thus, it is only during gametophyte generation do the gymnosperms produce haploid cells. This is true for any gymnosperm given that they are vascular plants.